Four dimensional topological field theory allows to define matter particles as charges of the gauge group
breaking the gauge symmetry at a point. This is analogous to Deser/Jackiw and t'Hooft particles in 3d gravity. The degrees of freedom of General Relativity can also be introduced by symmetry breaking of the same topological field theory. This provides a framework in which gravity and matter can be considered from a unified point of
view. In this framework we study scattering of matter particles due to quantum gravity effects.